Chronic Alcohol Exposure Alters Gene Expression in HepG2 Cells

Background: The liver is the primary site of alcohol metabolism and is highly vulnerable to injuries due to chronic alcohol abuse. Several molecular mechanisms, including oxidative stress and altered cellular metabolism, have been implicated in the development and progression of alcoholic liver disease. We sought to gain further insight into the molecular pathogenesis by studying the effects of ethanol exposure on the global gene expression in HepG2 cells. Methods: HepG2 cells were cultured in the presence or absence of 75 mM ethanol for 9 days, with fresh media daily. Global gene expression changes were studied using Affymetrix GeneChip (R) Human Exon 1.0 ST Arrays. Gene expression differences were validated for 13 genes by quantitative real-time RT-PCR. To identify biological pathways affected by ethanol treatment, differentially expressed genes were analyzed by Ingenuity Pathway Analysis software. Results: Long-term ethanol exposure altered the expression of 1,093 genes (false discovery rate = 3%); many of these changes were modest. Long-term ethanol exposure affected several pathways, including acute phase response, amino acid metabolism, carbohydrate metabolism, and lipid metabolism. Conclusions: Global measurements of gene expression show that a large number of genes are affected by chronic ethanol, although most show modest effect. These data provide insight into the molecular pathology resulting from extended alcohol exposure.